Wax compositions containing telemeric polyalkyl oxoesters



WAX coMrosmoNs CONTAINING TEIEMERIC POLYALKYL oxoEsrERs JohnPodlipnik,'Palos Heights, 11]., assignor to Sinclair IltleliningCompany, New York, N.Y., a corporation of me No Drawing. Filed July 1,1958, Ser. No. 745,808

6 Claims. (Cl. 260-285) The present invention relates to an improvedparaflin wax composition particularly adapted to meet certain needs incoating cellulosic articles such as paperboard containers useful in thepackaging of milk.

During the past several years considerable time and money have beenexpended in the development of various wax compositions suitable for useby the dairy industry such as for instance, in the packaging of milk inpaperboard cartons. This work has been, to a large extent, directed toimproving the resistance to bulging of the filled paper container due toa rippled coating and to the elimination of the tendency of the waxcoating, due to its inflexibility, to crack and flake during thehandling and storage of the milk. These difiiculties have been overcometo a large extent by the addition of such materials as polyethylene,various cuts of microcrystalline waxes, various paraflin waxes, etc-to abase crystalline parafiin wax. There has, however, been an additionalproblem not satisfied by any of the commercially available wax coatingcompositions on the market today and that is the formation of V-shapeddry spots in the wax coating on the inside of the carton panels. Thesespots represent portions of the coating where no wax is deposited on thepaperboard, which as in the case of ripples lead to excessive bulging.

The present invention provides a wax composition suitable for use 'onsuch containers and which when so applied results in a containersubstantially free of dry spots on the inside panels and which alsoprovides good protection against flaking, cracking, and rippling. Thepresent paraffin wax composition consists essentially of fouringredients which can be generally classified as a crystalline paraffinwax, a defined soft microcrystalline wax, polyethylene and a liquidtelomeric polyalkyl oxoester. This composition can be applied topaperboard containers which are dipped into a melt of the wax, forinstance, maintained at a temperature of about 155 to 190 F. The coatedcontainers are withdrawn from the vat of melted wax and then cooled bycontact with a flowing gas stream, e.g. air, preferably at a temperatureof about 40 to 60 F. Paperboard presently employed in the industry suchas sized and calendered paperboard produced by the Fourdrinier processand having a'low moisture content, e.g. about 6 percent or less can beused as the base material for the wax coating. I

The crystalline paraflin wax component of the instant composition cancomprise about 72 to 92 weight percent of the blend, preferably about80-85 weight percent and can be a fully or semi-refined wax. In generalthe wax can be obtained from parafiin base crude oils such asPennsylvania crude or mixed base crudes and will have a melting point ofabout 120 to 155 F. and a maximum oil content (ASTM D-72l-55T) of about1 percent. To provide a compositionof maximum utility the odor and tasteof the paraffin wax should be nil.

The soft microcrystalline wax ingredient is employed in amounts of aboutto 25 percent by weight, preferably about 12 to 18 weight percent of thecomposition, and has a petrolatum melting point (ASTM Dl27-49) of about90 F. to 160 F., a refractive index (n at 70 C. of at least about 1.45,a viscosity at 210 F. of about 15 to 25 centistokes (ASTM D-445-53T) andnot more 3,012,981 Patented Dec. 12, 1961 ice 2 than about 5.0 weightpercent oil (ASTM 72l-56T The addition of this ingredient to thecomposition provides enhanced flexibility andadhesion properties to thefinal blend. The soft microcrystalline wax can be obtained fromPennsylvania and Mid-Continent petrolatums. This wax is relativelyrich'in cycloparafiins, compared to the petrolatum from which it isderived, the cycloparatfin content of the wax including bothnon-condensed and condensed cycloalkanes, usually being at least about25 percent by weight. The soft microcrystalline wax which is utilizedcan be described as a heart cut" of the parent petrolatum resulting fromthe removal of both the most oily components and the most crystalline,leaving the desired microcrystalline wax fraction. This fraction isgenerally obtained by various combinations of deoiling procedures usingselective solvents such as for example, a mixture of methylethyl ketone,toluene and benzene.

The polyethylenes useful in the present invention can generally be anyof those wax-compatible, i.e. soluble or dispersible, polyethylenesknown to the art. For instance, they can be conventional polyethylenesof the general formula C H, obtained by polymerizing the ethylenemonomer; they can contain such groups as terminal -OH groups. Thus, theselection of the particular type of polyethylene, is of little moment.The main requirement is that its molecular weight be such that it iscompatible in the wax composition. The polyethylene is incorporated intothe wax compositions in order to overcome the sticking tendency of thesoft, tacky microcrystalline wax, to eliminate the rippled, serpentinecoating associated with straight petroleum wax, to give superiorflexibility, tensile strength and adhesion to the coating, and to reducepenetration into the paperboard and therefore consumption of the wax.Generally the maximum concentration of the polyethylene in the waxcomposition is governed by the viscosity of the final blend which mustbe less than about 10 centistokes at F., exceeding of which will resultin high wax consumption, excessive buildup on coating machine parts andcoatings having rough'surfaces. Usually, however, the polyethyleneconcentration will not exceed about 4.0 percent by weight of the finalblend. The minimum concentration of the polyethylene is generallyvcontrolled by flexibility and ad: hesion and will usually be at leastabout 0.5 percent by weight. The polyethylenes useful in the presentinvention in general have average molecular weights in the range ofabout 1,000 to 30,000; preferably the major portion not exceeding about10,000 and in particular we prefer to use polyethylenes having anaverage molecular weight in the range of about 2,000 to 4,000. Althoughpolyethylenes having molecular weights exceeding about 10,000 can beused they are generally to be avoided or minimized since flexibility maybe adversely affected unless the blend viscosity is increased beyond the10 centistokes value for obtaining'minimum wax consumption. If, however,the higher molecular weight polyethylenes are used the concentrationthereof in the total blend can with advantage be limited to a maximum ofsay about 0.5 weight percent for a 10,000 to 20,000 polyethylene andabout 0.1 weight percent for a 20,000 to 30,000 polyethylene. If theproportions of these higher molecular weight polyethylenes materiallyexceed these values the coating may be rough, although the objectionaldry spots and rippling would still be avoided. In any event themo'ecular weight of the polyethylene will usually lie in the range ofabout 1000 to 30,000 w th the amount and molecular weight being selectedto give a final composition having a viscosity of less than about 10centistokes at 175 F.

The fourth essential ingredient of the present composition is a materialcharacterized as being a wax com- 4 patible, liquid telorneric polyalkyloxoester represented Penetration atby the general structural formula 77F 19 o n 11 F 41 8-0 F 100 (g 5 5 Tenslle strength at 73 F., p.s.i 316Refractive index at 73 F 1.4317

(2) 15 weight percent of a soft rnicrocrystalline foots wherein'R is analkyl radical of from 1 to 12 preferably wax havin h f A ollowln h s art 2 to 6, carbon atoms, R is an alkyl radlcal of from 1 g g p y lcal chac ensues to 18, preferably 4 to 12, carbon atoms and n is an in- 10 rvity, API 32,6 teger from 2 .50 10. These compounds can be prepared etrlaium M.P-, F 156 by reacting together an aldehyde and an aliphaticester m i y, it 0 F 17.1 of a 4-carbon atom monoethylenic, unsaturateddicar- Percent 0.6 boxylic acid wherein the ethylenic linkage isconjugated Penetration t 7 F 68 with both carbonyl groups, in thepresence of a free radl cti e index at 70 F 1.45785 ical promoting agentsuch as ultraviolet radiation, acetyl P roxide, benzoyl p roxide,hydrogen peroxide, etc. For 0025 weight percent 9 a hqmd telomem polyadescription of the manner of preparing such compounds oxoesterappmxlmately 5) prepared by rereference is made to US. Patent No.2,647,920 issued to acting t9getber dl'z'ethylhexyl fumarat? andn'butyral' Patrick et 31,. It is preferred that the aldehyde be n- 20dehzde the presence bimzoylperoxlde' butymldehyde and the aliphaticester be diaemymaxyl Polyethylenes asundlcated m Table I below: Thefumatam Generally this component of the wax above blends were applied tohalf-gallon milk containers position need be present in only minorconcentrations in order to evaluate the effect of differentpolyethylenes of say for instance, about 10 to 100 part li and theconcentrations thereof on the consumption charf bl about to parts permillion This 25 acterlstics of the wax as well as the physicalappearance ponent of the wax composition is imperative to satisfacof thecontainer afiel: watlng- The P W Y used t paperboard m i production inthat it elimiare commercially available and they are listed in Table Ihates th for ti n f b bbl d h v-shaped d spots below along with theresults obtained. The base wax on the inside panels of th ca to a di iowhich so in the table is the mixture of ingredients 1, 2 and 3 above.other agents fail to overcome. The coating temperature in each case was180 F.

Table 1 Physical tests on blends Tests on coated milk cartons Avg. moi.Viscosity (ASTM Wax consumption, of poly- D445-53T) Flexllbs 1,000. Agal. ethylene bility at cartons Appearance 01' 60 F.' coating surfaceCS/l75F. CSI2IOF CartonA CartonB Base wax. 5. 80 4. 19 0.05 57. 2 59. 0Smooth. Basel d? I e 131 lane 2,000 051 4 as 0 10 2109; $lielhileneniiii7.15 4100 0124 543 57 5 Do. 3.07 polyethylene... 7.70 5.31 0.11 1.0%polyethylene 2,000 6.66 4. s4 0. 0e 2.07 polyethylene..- 7.97 4.90 0.1951.8 55.0 D0. 3.0% polyethylene--- 0.18 5.18 o. 17 1.0% polyethylene2,500 6. 89 4.85 0. 06 2.0% polyethylene.-- 7. 51 5. 32 0.10 Do. 3.0%polyethylene-.- & 58 5. 94 0. 12 1.0% polyethylene..- 4,000 0. 59 4. 71(l. 13 2.0% polyethylene..- 7.42 5.23 0.23 54.8 58.3 Slightly rough.3.0% polyethylene.-- 8.45 5.99 0.12 1.0g, polyethylene.-- 7,000 7. 06 5.02 0.06 2.0 a polyethylene 8.38 6. 05 0. 19 54. 9 59. 1 Smooth. 3.0%polyethylene 11.01 a 80 0. 20 0.5% polyethylene 8. 29 4. 91 0.04 1.0%polyethylene.. 5.59 0.06 52.5 54.6 Rough. 2.07 polyethylene 12.04 1.050.00 00.0 02.1 Very rough. a.% polyethy 1s. 51 s. 0.20 0.25%polyethylene..-" 23,000 10.12 4.80 0.06 50.4 52.5 Rough. 0.507polyethylene... 18.53 5.08 0.07 61.9 66.6 Veryrough. igl polyethylene13. 1. 04 o. 09 2. polyetllylene.-- 11.79 0.12

1 Values represent deflection at break-in inches determined by bending abeam of wax on an lnstron tester at 2 in. min. crosshead s i T ispolyethylene ad terminal 'OH groups.

I Can't run.

The present invention can best be illustrated by the following specificexamples.

In order to determine the efiect of the various polycthylenes and theconcentration thereof upon the wax compos'tion of the instant inventionseveral blends were prepared by mixing at elevated temperatures, e.g.180' F., the following ingredients.

(1) 83 weight percent of a crystalline paraflin wax having the followingphysical characteristics:

.17 wax composition in eliminating the formation of dry spots were asfollows:

in the wax coating after application to milk containers severalcompositions were prepared, and tested on halfgallon milk cartons. Theprocedure used in coating the cartons was as follows. The wax blend wasplaced in a dipping vat maintained ata temperature of between 165COMPOSITION A This composition was composed of about 90.25 weightpercent crystalline paraflin wax having the characteristics set forth in(1) above; about 4.0 weight percent of a microcrystalline wax having agravity of 33.9 API, a petrolatu'rn melting point of about 170.6 F., aviscosity of about 24.27 centistokes at 175 F., and an oil content 'ofabout 1.45%; about 5.0 weight percent of a heavy lube distillate footswax having a gravity of about 38.1 API, an ASTM melting point of about118.0 F., a viscosity of about 1.01 centistokes at 175 F. and arefractive index at 70 C. of about 1.4424; and about 0.75 weight percentof a tank bottoms microcrystalline wax having an ASTM melting point ofabout 197.5 F., penetration at 77 F. of 7. The physical characteristicsof this blend were as follows:

This blend was used as a standard of comparison since it has goodproperties regarding its resistance to flaking, cracking, serpentine,mottling and flexibility although cartons coated therewith have thecharacteristic dry spots.

COMPOSITION B This composition is comprised of 83.0 weight percent ofthe paraffin wax set forth in (1) above, about 15 weight percent of thesoft microcrystalline wax set forth in (2) above and about 2 weightpercent of polyethylene having a molecular weight of about 2000.

COMPOSITION C This composition is the same as composition B having addedthereto .001 to .005 weight percent of the agent set forth in (3) above.

COMPOSITION D Same as composition B having added thereto 0.001 to .002weight percent of Dow Cornings Antifoam A which is a methyl siliconepolymer absorbed on a silica gel base.

COMPOSITION E Same as composition B having added thereto .001 weightpercent Dow Cornings D.C.F. 200-100 fluid which is a liquid methylsilicone polymer having a viscosity of about 100 cs. at 25 C.

Composition A was applied to half-gallon milk containers in the mannerset forth above so as to obtain data to check against the new wax and tosee that the coating machines were operating properly. Data on thecartons for these tests are summarized in Table H below.

The compositions tested.

Table II COMPOSITION A Carton. No. 1 No 2 Properties of finishedcartons:

Weight of carton, unwaxed 61. 0 59.9 Weight of wax. grams 28. 9 26.0Weight of wax, lbs/1,000 cartons 63. 6 67. 2 Coverage, top flaps GoodFair Dry spot rating, bottom 1 1 2 Dry spot rating, to drain panel 0 2Dry spot rating, si e panels 1 0 0 Dry spot rating, bottom drain panel 1Coating smoothness Good Good Bubbles Few Few 1 Rating used in alltables:

0= Excellent, no dry spots.

l=Very good ood Determined by number, size and position oi dry 2- G 3=Fair spots.

4= Poor 5= Very poor, over 75% of carton panel covered.

The cartons coated with this composition have good qualities with theexception, however, of the presence of bubbles and dry spots in thebottoms of all the cartons.

The new wax composition minus the oxoester additive (composition B) wastested on half-gallon milk cartons in order to compare its efiectivenesswith composition A. These data are summarized in Table III below.

Table III Carton No. 1 No. 2 No 3 Properties of finished cartons:

Weight of carton, unwaxed, gins 63. 4 58.5 60. 3 Weight of wax, gms 22.4 29. 8 24. 5 Weight of wax, lbs./1,000 cartons- 49. 3 65. 6 53. 9Coverage, top flaps Exc. Good Exc. Dry spot rating, bottom 1 0 0 Dryspot rating, to drain pane 2 1 0 Dry spot rating, 51 e panels 1 0 0 Dryspot rating, bottom drain panel 0 0 0 Coating smoothness Good Fair GoodBubbles on bottom of carton 1 Numerous bubbles.

It is to be noted that the containers coated with composition B comparevery favorably with containers coated with composition A in coveragerespects and in addition indicate a decrease in wax consumption; alsocoverage on the top flaps is improved to some extent. There were still,however, numerous air bubbles formed on the bottoms of the cartons alongwith dry spots none of which could be eliminated by varying immersiontime in the wax, coating temperatures or the paperboard. Although themottling was more pronounced on the cartons using composition B thancomposition A, this eifect appears to be primarily a function of theproperties of the paperboard container. This feature however is notconsidered objectionable by the dairy industry and hence is of littleimport.

When, however, cartons were prepared using composition C as the coatingmaterial the bubbles and dry spots on the cartons were eliminated,giving excellent wax coatings in all respects when applied to thepaperboard container. The data for these cartons is set forth in TableIV below- Table IV COMPOSITION C Carton-.. No. 1 No. 2 No. 3 No. 4 No. 5

Amount of agent (3) 005 001 001 005 001 Properties of finished cartons:

Weight of carton, un- 62 4 58. 9 61. 6 61.8 60. 0

waxed. Weight of wax, grams. 22. 9 26.1 21. 9 24. 0 23. 0 Weight of wax,lbs/1,000 50. 4 57. 4 48. 2 52. 4 50. 6

cartons. Coverage, top flaps Exc Good Exc. Exc. Exc. Dry spot rating,bottom- 0 1 0 0 0 Dry spot rating, top 0 0 0 0 0 drain pmel. Dry s atrating, side 0 0 0 0 1 ane s. Dry spot rating, bottom 0 0 0 0 0 drainpanel Coating smoothness"-.. V.G. Good V.G. V.G. V.G. Bubbles None NoneNone None None In addition to providing a container having the bubblesand dry spots eliminated therefrom, the addition of the telomericoxoester tov the wax composition B (composition C) gave a better surfaceappearance in that before addition the. coating was slightly grainywhereas after addition the coating was much smoother. Here again, as incomposition B mottling was noticeable but not detrimentally so. Thecomposition also maintained its good consumption rate.

Two alternative polymer agents were tested in the composition in orderto ascertain the effectiveness of the oxoester in eliminating the dryspots. They were Dow Corning Antifoam A and Dow Corning DFC 200-100Fluid. The Antifoam A is a solid silica gel containing methyl siliconepolymer and was added to the composition both by means of a solvent anddirectly into the wax whereas DFC 200-100 is a liquid methyl siliconepolymer and was added directly to the wax as such. Neither of theseagents proved eifective in eliminating the dry spots or the bubbles inthe instant composition as shown by the data summarized in Table Vbelow.

Table V Composition Composition Com D-Agent added DAgent added sitlofidirectly to wax in solvent Agent concentration: I

Weight percent 0. 001 0. 002 0. 001 0. 001 0. 001 Parts per million 1020 10 10 10 Carton No. 1 No. 2 No. 3 No. 4 No. 5

Properties of finished carton:

Weight of carton, un- 59.1 03.0 58.8 29.0

waxe gms. Weight of wax, gms 28.0 23. 3 28. 2 15. 2 Weight of wax,lhs.,'100 61.6 61.3 62.0 33.4 cartons.

Coverage, top flops Fair Exc. Good Exc. Exc Dry spot rating, bot- 1 1 0Dunn.t t ting to 3 1 2 0 3 P P drain eL Dryspqot rating, side 1 0 1 0 3pane l Dry spot rating, bottom 0 0 0 0 3 drain e1. Coatingsmoothness.---. Poor Fair Poor Exc. Poor Bubbles 1 Explanation of ratingsystem given in Table II. I Numerous.

As here shown cartonscoated with the present wax composition usinginstead of the oxoesteradditive other agents fail to obtain relief fromthe presence of dry spots and bubbles. Additionally the cartons coatedwith these compositions had less desirable properties in respect tosmoothness of coating and top flap coverage. In some cases, it will alsobe noted that the dry spot ratings were actually increased slightly bythe use of these components.

From the above data it can readily be seen that by the present inventionI have provided a wax composition which enables the production ofpaperboard cartons having improved properties in regard to the majorproblem of dry spot formation, as well as having excellent properties inall other respects, such as coating smoothness and wax consumption.

In addition to giving excellent coverage and the elimination of dryspots and bubbles, containers coated with the new composition containingthe oxoester additive showed a greater deposition of wax on the topflaps of the container with no difiiculty being encountered with heatsealing the flaps and no top leakers resulting on either quart orhalf-gallon containers. As revealed in Tables H and IV the consumptionof the new wax was markedly less (about 10 to 12%) than given bycomposition A with coating temperatures of about 180 F. proving the mosteflicient.

, '8 Another composition was prepared using, however, as a base wax acrystalline parafiin wax having the following physical characteristics:

Gravity, API- 42.2 Viscosity, cs./175 F 4.827 ASTM, M.P., F 128.2Percent oi .03 Penetration at- F 86 Refractive index at 70 C 1.43215 Inall other respects the ingredients were the same as set forth incomposition C above, as were the amounts blended. This composition alsoresulted in a paperboard container substantially. free of dry spots onthe inside panels and having excellent coverage and resistance toflaking and cracking.

The microcrystalline wax component of the present invention can also bevaried if desired. For instance, mircocrystalline waxes having higherpercentages of lower melting components rich in cycloalkanes can beused. Thus, fractions identifiable by the following characteristics canbe incorporated in the blend rather than that set forth specifically in(2) above:

The melting point of all these wax fractions depends primarily upon theextent of deoiling and removal of the lower melting components rich inthe cycloalkanes. Thus, component (2) above having a cycloalkane contentof about 30% has a higher melting point than waxes A and p B and wasprepared by more extensive conventional de oiling procedures than werewaxes A and B.

I claim:

l. A wax composition consisting essentially of abou 72 to 92 weightpercent of a crystalline paraflin wax having a melting point of about toF. and a maximum oil content of about 1.0 weight percent, about 5 to 25weight percent of a microcrystalline wax having a petrolatum meltingpoint of about 90 to F., a viscosity at 210 F. of about 15 to 25centistokes, a minimum refractive index at 70 C. of about 1.45, and anoil content not exceeding about 5.0 weight percent, about 0.5 to 4Weight percent of polyethylene having an average molecular weight ofabout 1000 to 30,000 and about 10 to 100 parts per million of a liquidtelomeric polyallryl oxoester having the structural formula:

.ilii 1 if].

References Cited in the file of this patent UNITED STATES PATENTSRumberger June 16, 1953 Patrick et al Aug. 4, 1953 Anderson Dec. 27,1955 Smith Ian. 31, 1956 Bailly et a1 Aug. 7, 1956 Backlund May 7, 1957Jakoitis Oct. 1, 1957

1. A WAX COMPOSITION CONSISTING ESSENTIALLY OF ABOUT 72 TO 92 WEIGHTPERCENT OF A CRYSTALLINE PARAFFIN WAX HAVING A MELTING POINT OF ABOUT120* TO 155* F. AND A MAXIMUM OIL CONTENT OF ABOUT 1.0 WEIGHT PERCENT,ABOUT 5 TO 25 WEIGHT PERCENT OF A MICROCRYSTALLINE WAX HAVING APETROLATUM MELTING POINT OF ABOUT 90 TO 160* F., A VISCOSITY AT 210* F.OF ABOUT 15 TO 25 CENTISTOKES, A MINIMUM REFRACTIVE INDEX AT 70* C. OFABOUT 1.45, AND AN OIL CONTENT NOT EXCEEDING ABOUT 5.0 WEIGHT PERCENT,ABOUT 0.5 TO 4 WEIGHT PERCENT OF POLYETHYLENE HAVING AN AVERAGEMOLECULAR WEIGHT OF ABOUT 1000 TO 30,000 AND ABOUT 10 TO 100 PARTS PERMILLION OF A LIQUID TELOMERIC POLYALKYL OXOESTER HAVING THE STRUCTURALFORMULA: